t.i.d. (on prescription)

t.i.d. means three times a day. It is an abbreviation for "ter in die" which in Latin means three times a day. The abbreviation t.i.d. is sometimes written without a period either in lower-case letters as "tid" or in capital letters as "TID". It is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken.